Cepheid Variable Stars & Distance Determination
Discovery of the Period - Luminosity Relationship
Calculating Distances Using Cepheids
Standard Candles
The Hubble Key Project ...
Cepheid Variable Star :
A Cepheid variable star one of a class of variable stars whose periods (i.e., the time for one cycle) of variation tend to be proportional to their luminosity and that are therefore useful in measuring interstellar and ...
Cepheid Variable Stars
Cepheid variable stars are stars that periodically pulsate because of an instability in their internal structure.
Cepheid variable star
Cepheid variables, named after the first star discovered of this type, Delta Cephei, are stars that are seen to vary in brightness on a very regular timescale.
Cepheid Variable Stars: A luminous giant star whose brightness varies periodically: growing very bright quickly, and then dimming slowly. The period of variation is related to luminosity.
Cepheid Variable Star
Variable stars with a period of 1-60 days. Their period is related to luminosity.
Chandrasekhar Limit ...
A Cepheid Variable Star
Polaris A is a pulsating variable star of a type known as a Cepheid variable, after prototypical star of this type, Delta Cephei. Cepheid variables are bright, giant stars that show periodic variations in luminosity.
Cepheid variable stars have masses between five and twenty times the mass of our Sun. The more massive stars are more luminous and have more extended envelopes (the outer layers of gas in a star are sometimes called its "envelope").
Cepheid variable Star whose luminosity varies in a characteristic way, with a rapid rise in brightness followed by a slower decline.
Cepheid variable star: A star with periodic variations in magnitude (brightness).
Challenger: The second space shuttle to be launched into orbit. It was destroyed in 1986 after an explosion occurred a few seconds into flight.
Cepheid Variable Stars: A type of luminous giant star whose luminosity varies in a periodic fashion. Cepheids are characterized by a rapid rise in luminosity followed by a slow decline.
CEPHEID VARIABLE STARS
Cepheid variables are supergiant stars that regularly pulsate in size and change in brightness. As the star increases in size, its brightness decreases; then, the reverse occurs. The luminosity is proportional to the period.
Cepheid variable stars are pulsating stars, named after the first known member of the class, Delta Cephei. These stars pulsate because the hydrogen and helium ionization zones are close to the surface of the star.
2. A Cepheid variable star in the Virgo cluster has an absolute magnitude of "5 and is observed to have an apparent magnitude of 26.3. Use these figures to calculate the distance to the Virgo cluster. (Hint) ...
Some Cepheid variable stars can be found in this constellation: W Sgr is a supergiant which brightness fluctuates every 7 days and 14 hours between 4.4 mag and 5.0 mag.
The supergiant (spectraltype G1.5Ib) U Sgr lies close to center of M25.
period-luminosity relation how the average luminosity of Cepheid variable stars depends on their period of pulsation. photon a distinct ``chunk'' or particle of electromagnetic radiation.
on a detailed star map and note with some excitement that Pi PsA, a fifth magnitude (5.11) class F dwarf (given as F0+F3) in Piscis Austrinus (the Southern Fish) well to the south of first magnitude Fomalhaut, is marked as a Cepheid variable star, ...
In 1912 the astronomer Henrietta Leavitt (see Fig. 1) observed 20 Cepheid variable stars in the Small Magellanic Cloud (SMC).
1784 - Edward Piggot discovers the first Cepheid variable star
1838 - Thomas Henderson, Friedrich Struve, and Friedrich Bessel measure stellar parallaxes ...
There are two types of Cepheid Variable star. The original 'classical' Type I Cepheid Variables are metal-rich yellow supergiant stars in the late F to early K parts of their lives.
In 1929, Edwin Hubble published his conclusion, based on his observations of Cepheid variable stars in distant galaxies, that the universe was expanding.
In 1912 Henrietta Leavitt discovered Cepheid variable stars in the Magellanic Clouds and confirmed that the variables with longer periods had larger luminosities. By the mid 1920s J. C.
W VIRGINIS STAR - Another name for Type II Cepheid variable stars.
WADSLEYITE - High pressure polymorph of olivine, β-Mg2SiO4, found on Earth and in some meteorites.
To accomplish this, they used individually resolved Cepheid variable stars within M31. Cepheid variable stars are very useful in calculating distances to many nearby galaxies.
Also included among Population I are the Cepheid variable stars. Cepheids have become one of the standard distance indicators for galactic and extragalactic research through their period-luminosity relation and its validity from galaxy to galaxy.
Edwin Hubble settled the debate in 1925 when he identified extragalactic Cepheid variable stars for the first time on astronomical photos of M31. These were made using the 2.
Polaris is a blue-green Cepheid variable star (its size brightness changes periodically, with period of 3.969778 days; it varyies between mag 1.92 and 2.07). Polaris has a relatively dim companion star (9th magnitude).
Delta Cephei,is a prototype for what are now called Cepheid variable stars. The study of stars such as these helps astronomers determine distance.
On the scale of largest-known stars, Cepheus boasts three in the top five! ...
A type of II Cepheid, one of the fainter class of Cepheid variable stars characteristic of Cepheids in globular clusters.
x radiation - (n.)
electromagnetic radiation in the range of approximately 0.05-100 A.
A relationship that describes how the luminosity or absolute brightness of a Cepheid variable star depends on the period of time over which that brightness varies.
Planetary Nebula ...
Delta Cephei is the prototype of the Cepheid variable stars, and it is among the closest stars of this type to the Sun (with Polaris being closer).
period-luminosity relationship
The predictable relation between the pulsation period and changes in luminosity of a Cepheid variable star.
perturbation
Small deviances in the location of a star, visible through large telescopes.
The relationship between the mean luminosity of a Cepheid variable star and the period of its changes.
PHASE ...
A pulsating star in the constellation Aquila. It was the first Cepheid variable star discovered, in 1784. [C95]
Etalon ...
Period-luminosity Relationship - The relationship between the period of brightness variation and the luminosity of a Cepheid variable star. The longer the period of a Cepheid is, the more luminous the Cepheid ...
Its most celebrated star is Delta Cephei, a pulsating supergiant star that varies in brightness every 5.4 days. It is the prototype of the Cepheid variable stars that astronomers use for estimating distances in space.
While studying Cepheid variable stars in the SMC, Henrietta Leavitt discovered (1912) the period-luminosity relation. This relation offered a technique for measuring the distances of stars and galaxies. In Feb.
These are located at the low luminosity end of the instability strip and they have periods less than a day. RR lyrae stars are good for relatively near by distances. Cepheid variable stars are so luminous that they can be used to get the distances ...
 See also: Cepheid, Variable star, Cepheid Variable, Period, Distance
  
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